Whole genome sequencing reveals biosynthetic potential of Novel Actinobacteria strains isolated from the sub-Antarctic Marion island terrestrial environments.
Kipandula, W.*1,2, Dloboyi, A.1, Matcher, G. F.3, Dorrington, R.1,3
1 Department of Biochemistry and Microbiology, Rhodes University, Makhanda, South Africa
2 Kamuzu University of Health Sciences (College of Medicine), P/bag 360, Blantyre, Malawi.
3 South African Institute for Aquatic Biodiversity, Makhanda. South Africa
Recent efforts in natural products drug discovery research have focused on unsurveyed and, extreme ecological niches as sources of antibiotic producing microbes. This has led to our interest in cold-adapted bacteria from the Sub-Antarctic Marion island terrestrial environments. Here, we explored the potential of the sub-Antarctic Marion island bacterial isolates, especially those from the phylum Actinobacteria, as sources of novel antimicrobial natural products. We used a combination of culture-dependent and culture-independent methods to isolate strains with bioactivity, and used recent in silico genome mining tools to identify putative biosynthetic gene clusters(BGCs) and characterize antimicrobial metabolites they encode. Analysis of draft whole-genomes revealed four of the five isolates as potentially novel Actinobacteria species. Across the draft genomes, a total of 138 biosynthetic gene clusters were detected, of which over half displayed less than 50% similarity to known BGCs. Some BGCs formed similarity networks with known BGCs from MiBIG repository, encoding compounds such Rustmicin, Bafilomycin, Alpiniamide and Griseobactin. However, a large number of the detected BGCs had no homology with any known BGCs, including RiPP Class II lanthipeptides BGCs in three isolates which shared no similarity with any gene cluster identified so far suggesting that these are novel BGCs with the potential to encode novel compounds. This study demonstrates the value of polar microbiomes as a source of novel microbial life with promising and exploitable biosynthetic potential. It further provides a genomic platform for future bioengineering efforts of the novel BGCs detected and characterization of their secondary metabolites they encode.
